Passage
knowing this first, that there shall come at [the] close of the days mockers with mocking, walking according to their own lusts,
knowing this first, that there shall come at [the] close of the days mockers with mocking, walking according to their own lusts,
2 Peter 3:1 This, a second letter, beloved, I already write to you, in [both] which I stir up, in the way of putting you in remembrance, your pure mind,
2 Peter 3:2 to be mindful of the words spoken before by the holy prophets, and of the commandment of the Lord and Saviour by your apostles;
2 Peter 3:3 knowing this first, that there shall come at [the] close of the days mockers with mocking, walking according to their own lusts,
2 Peter 3:4 and saying, Where is the promise of his coming? for from the time the fathers fell asleep all things remain thus from [the] beginning of [the] creation.
2 Peter 3:5 For this is hidden from them through their own wilfulness, that heavens were of old, and an earth, having its subsistence out of water and in water, by the word of God,
The verse centers on "knowing", "first", "shall", "come", "close", "days", "mockers", and "mocking". It is saying that the verse draws attention to "knowing" and "first", so its meaning should be read from those terms before moving to application.
The nearby context moves from verse 2's "to be mindful of the words spoken..." into verse 4's "and saying Where is the promise of...", so "knowing" and "first" belong inside that flow. In 2 Peter context, the local focus is Christ, faith, and discipleship.
A plain takeaway is to answer the verse's own emphasis on "knowing" and "first" with trust shaped by these words, not by a vague optimism outside the passage.